Schottel thrusters to propel Washburn & Doughty tug

Written by Nick Blenkey
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Schottel has been selected to equip the new tugboat under construction for the Saint Lawrence Seaway Development Corporation (SLSDC)

The tugboat currently under construction at the Washburn & Doughty Associates, Inc. shipyard in East Boothbay, Maine, for the Saint Lawrence Seaway Development Corporation (SLSDC) will be propelled by medium-sized Schottel azimuth thrusters.

The tug is being built to Glosten’s HT-60 design, the smallest in the harbor tug series developed by the Seattle-based naval architecture firm. It is scheduled for delivery in 2021.

Craig Middlebrook, Deputy Administrator of the SLSDC: “This new vessel will be used to carry out a variety of construction and maintenance duties for the U.S. portion of the St. Lawrence Seaway. These duties include routine maintenance of lock gates, maintenance and positioning of aids to navigation, ice management and removal of accumulated ice from lock walls.”


The tug’s two Schottel type SRP 210 FP Rudderpropellers (500 kW each) with propellers measuring 1.4 meters in diameter are powered by a pair of EPA Tier 3 diesel engines. As a result, the ASD tug will achieve a free running speed of approximately 14.5 knots. The thrusters will be equipped with Schottel’s patented and DNV-GL type-approved LEACON system, which ensures permanent monitoring of the propeller shaft and steering seals. Considered as a non-oil-to-water interface, this system complies with VGP regulations without the need to use environmentally acceptable lubricants (EALs).

With medium-sized Rudderpropellers such as the SRP 210, Schottel is meeting new challenges in the international maritime market.

At 18.30 meters in overall length, the tug is the right size for maneuvering inside lock chambers. At the same time, it has an 8.50-meter beam for improved performance in ice and enhanced stability for deck crane operations.


By offering medium-sized Rudderpropellers, Schottel is meeting new challenges in the international maritime market. These include shiftingd engine power classes, new ice class rules and the growing trend towards electric or hybrid-driven vessels. Combining the latest technologies in mechanical engineering, hydrodynamics, and digitalization, the medium-sized thrusters are available in three sizes which correspond to common engine power classes: SRP 210 (560 kW), SRP 240 (750 kW) and SRP 270 (900 kW).

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